The present invention involves method and apparatus for analyzing two measured signals that are modeled as containing primary and secondary portions. Coefficients relate the two signals according to a model defined in accordance with the present invention. In one embodiment, the present invention involves utilizing a transformation which evaluates a plurality of possible signal coefficients in order to find appropriate coefficients. Alternatively, the present invention involves using statistical functions or Fourier transform and windowing techniques to determine the coefficients relating to two measured signals. Use of this invention is described in particular detail with respect to blood oximetry measurements.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A system for the enhancement of physiological signals for the measurement of blood oxygen in a subject, the system comprising: first and second light sources to direct light toward the subject, said first and second light sources producing light of first and second wavelengths, respectively; a light detector positioned to detect said first and second light signals after interaction with the subject and to generate first and second signals indicative of an intensity of said first and second detected light signals, respectively, said first generated signal having a first portion arising from light transmitted from said first source and a second portion arising from a first interference source, said second generated signal having a first portion arising from light transmitted from said second source and a second portion arising from a second interference source; a packet generator to generate a plurality of data packets derived from data comprising said first and second generated signals; wherein said first and second portions of said first and second generated signals and a ratio of said first portion of said first generated signal to said first portion of said second generated signal have a mathematical relationship; and a calculator using said mathematical relationship to generate at least first and second functions from said plurality of data packets, said at least first and second functions having a final solution value indicative of said ratio.
2. The system of claim 1 wherein said ratio is indicative of blood oxygen saturation in the subject, the system further including a look-up table containing data relating said ratio to said blood oxygen saturation.
3. The system of claim 1 wherein at least one of said data packets comprises filtered data from at least one of said first and second generated signals.
4. The system of claim 1 wherein at least one of said data packets comprises a component of at least one of said first and second generated signals with the DC removed.
5. The system of claim 1 wherein at least one of said data packets is derived from a group of signals comprising said first generated signal, filtered data from said first generated signal, said second generated signal, filtered data from said second generated signal, and filtered data from a combination of said first and second generated signals.
8. A method using a computer for the enhancement of physiological signals for the measurement of blood oxygen in a subject, the method comprising the steps of: directing first and second light sources toward the subject, said first and second light sources producing light of first and second wavelength, respectively; detecting first and second light signals after interaction with the subject and generating signals indicative of an intensity of said first and second detected light signals, said first generated signals having a first portion arising from light transmitted from said first source and a second portion arising from a first interference source, said second generated signal having a first portion arising from light transmitted from said second source and a second portion arising from a second interference source; generating a plurality of data packets derived from data comprising said first and second generated signals, and using a mathematical relationship of said first and second portions of said first and second generated signals and a ratio of said first portion of said first generated signal to said first portion of said second generated signal to generate at least first and second functions from said plurality of data packets, said at least first and second functions having a solution value indicative of said ratio.
9. The method of claim 8 wherein said ratio is indicative of blood oxygen saturation in the subject, the method further including the step of using a look-up table containing data relating said ratio to said blood oxygen saturation to determine the blood oxygen level in the subject.
10. The method of claim 8 wherein at least one of said plurality of data packets comprises filtered data from said first generated signal.
11. The method of claim 8 wherein is at least one of said plurality of data packets comprises a component of said first generated signal with the DC removed.
12. The method of claim 8 wherein at least one of said plurality of data packets is derived from a group of signals comprising said first generated signal, filtered data from said first generated signal, said second generated signal, filtered data from said second generated signal, a combination of said first and second generated signals, and filtered data from said combination of said first and second generated signals.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
November 17, 1998
February 5, 2008
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